Fusing apparatus for dental casting.



L. H. LANIER.

FUSING APPARATUS FOR DENTAL CASTING.

I APPLICATION FILED JAN. 22. sIe.

1 1 99,28 1 Patented Sept. 26, 1916.

L H- Lama UNITED STATES PATENT onrrcn.

LEWIS H. LANIER, or convent, OKLAHOMA.

FUSING APPARATUS FOR DENTAL CASTING.

To all whom it may concern Be it known that I, LEWIS H. LANIER, a citizen of the United States, residing at Cordell, in, the county of Washita and State of Oklahoma, have invented certain new and useful Improvements in Fusing Apparatus for Dental Casting, of which the following is a specification, referencebeing had to the accompanying drawings.

This invention relates to devices for fusing or casting, and particularly to means for fusing gold or other metals and casting dental inlays.

In casting dental inlays or other like work to -day, an investment cup is used within whichthe casting is made, the molten metal being forced into the investment cup through the sprue hole thereof either by the action of a vacuum or by the action of centrifugal force. A button of gold or other metal is placed upon the top of the investment and then melted by means of a blow pipe, as for instance, an acetylene blow pipe, a gasolene blow pipe, or an oxyhydrogen blow pipe: The gasolene blow pipe gives a temperature of about 3000 degrees Fahrenheit. The oxyhydrogen andacetylene blow pipes give a temperature of approximately 4000 degrees Fahrenheit. This temperature is not suificient to secure the very best results in casting or refining, and it is the main object of my invention to provide means whereby the gold or othermetal may be submitted to the action of an electric arc which will give a temperature of 5300 degrees Fahrenheit, thus securing a much better fusing of the metal, rendering it more liquid and thdrefore putting it in better condition for successful casting.

Another object of my invention is the provision of means for this purpose which may be used either with a centrifugal casting machine or with a vacuum casting machine, or by direct pressure as on hinge machines.

Still another object of the invention is to provide a mechanism of this character including a carbon electrode adapted to be manipulated by the hand and brought into adjacency with the button in order to fuse the latter and a rheostat whereby the amount of current passing through the electrode may be controlled.

\ Still another object is to provide means whereby the melting devices, as before Specification of Letters-Patent.

Patented Sept. 26, 1916.

stated, may be operatively connected to a zentrlfugal castlng machine of the ordinary ype.

Other pb'jects will be disclosed in the ac companying specification.

My invention is illustrated in the accompanying. drawings, wherein: Figure 1 is a view showing in section the investment cup, the carbon block and the movable electrode, and in top plan view the rheostat for control hug the current; Fig. 2 is a partially diagrammatic top plan view of a centrifugal casting machine, showing the application of my invention "thereto; Fig. 3 is anenlarged partial sectional elevation showing the manner in which the bar 31 is rotated; Fig. 4. is a longitudinal sectional view of the carbon block and the investment cup; Fig. 5 is a section on the line 5-5 of Fig. 4:.

I will first describe the construction in connection with an ordinary investment cup such as is used in connection with the Elgin vacuum casting machines or hinge machines, as this is the simplest manner in which my invention may be applied.

Referring to Figs. 1, 2 and 4, 2 designates an investment cup or ring of any ordinary or suitable form adapted to vacuum casting. This investment cup incloses the investment material 3, formed to provide the usual sprue opening 4 leading into the mold cavity 5 formed in any usual or suitable manner. Thisinvestment cup under ordinary circumstances is a piece of brass tubing about of an inch thick, {7 inch in diameter, and from 1% to 2% inches long. Mounted upon the investment cup is a carbon block 6 which may be made of the same material from which electric light pencils are made, which is formed upon its upper face with a depression 7 having a sprue opening 8 extending through the block, and, when the blockis in place upon the investment cup,

registering with the sp'rue opening l thereof. Either the block 6 for a portion of its length is cut away to fit over and telescope upon the investment ring, or as illustrated, the investment ring extends beyond the investment 3' and telescopes over the carbon block.

Operating in connection with the carbon block is a rheostat comprising a base 9 which may be made of marble or any other suitable material and which has mounted upon it a rheostat coil 10. This coil is too the rheostat in a manner well understood.

Operating in connection with the contacts 16 is a key 17 which is movable into on gagement with any one of the contacts 16. This key is electrically connected by .any suitable conductor 18 to a bindingpost 19. The base 9 is also provided with a binding post 20. Engaging the binding posts 14 and 20 are the wires 21 leading from any suitable current supply: Leading from the binding post 19 is a wire 22 which is electrically connected in any suitable manner to the carbon receptacle or block 6. Leading from the binding post 20 is a wire 24. which is connected to a metal core 25 passing through a handle 26 of insulating material. The metallic core 25 is operatively connected to a metallic ferrule 27 and electrically connected to this ferrule 27 and to the core 25 is attached a carbon rod 28. This carbon rod in actual practice is about 6 inches long only been shown for illustration.

and approximately one-half inch in diameter and forms an electrode.

The operation of this form ofmy invention will be obvious. When it is desired to perform a casting operation a button of metal, as for instance, gold, is placed in the hollow 7 of the block 6. The current is then turned on and the member 17 adjusted so as to secure the proper strength of current.

The electrode 28 is then approximated to the metallic button and an electric arc is med between the button and the electro e 28 which fuses the button. As soon as the button is properly fused, the valve (not shown) which controls the connection of the investment cup with the vacuum chamber of the Elgin mechanism is turned and the molten metal is sucked into the investment cup.

In Fig. 2 I have shown myinvention as applied in connection with a centrifugal casting machine. All the parts of the rheostat and the electrode 28 and its handle 26 are exactly the same as previously described. Therefore the same reference numerals have been used for these parts. The centrifugal casting apparatus forms no part of my invention as it is old and well known and has It consists of a metallic base 29 upon which is mounted a shaft or pedestal 30, this shaft being mounted in ball bearings and carrying a metallic bar 31 which in the ordinary form of this apparatus is about one inch wide and twelve inches long and about oneeighth of an inch thick. A spring motor, designated generally 32, is operatively connected to the shaft or pedestal 30 so as to rotate the latter. A latch 33 is designed to hold the shaft against the action of the spring, and when this latch is released the spring will cause the rotation of the "shaft 30 and the bar 31. Inasmuch as all of these details are old and well known it is not necessary to describe them further.

Mounted upon one endof the bar 31 is a sliding weight 34 which may be shifted along the bar and held in its adjusted position by means of a set screw. The opposite end of the bar 31 carries upon it the metallic sleeve 35 which is cut away upon its upper face as at 36 and which is held to the bar in any suitable manner. This metallic sleeve 35 is designed to support the carbon receptacle and the investment cup. The investment cup is of the form previously described and is designated 35 in Fig. 4. The carbon receptacle consists of a block of carbon 36 which is about 4 inches long and 1 inch in diameter. At one end the carbon block is so formed as to telescopically engage with the investment ring and at this end the carbon block is formed with a vertically disposed slot or groove 37 about of an inch wide and 5* of an inch deep which extends inward from the end of the block which confronts the investment and intersecting this groove 37 is a depression 38 having the form of a half moon. This depression is 1 inch wide and is cut in the side of the carbon block or receptacle and extends nearly to the bottom of the groove 37. The crescent shape of the depression 38 permits the operator to use the carbon pencil or electrode 28 to the best advantage in fusing gold. The end of the investment which confronts the groove 37 is made concave so that.

the molten metal will be directed toward the sprue opening 39 and allow no scattering of the molten metal.

With the construction as abovedescribed, a button of gold or other metal is placed within the depression 38 and the carbon pencil or electrode 28 is brought into proximity thereto and the current turned on. An electric arc will thus be formed between the electrode and the button which will cause the melting of the button at a very high temperature. As soon as the metal has been liquefied to the proper degree the carbon pencil is withdrawn and the latch 33 is released, whereupon the spring motor will cause the bar 31 to rotate at a high velocity and the centrifugal force will cause the gold or other molten metal to be forced outward and into the mold cavity in the investment through groove 37.

The particular form of centrifugal machine used is immaterial, and it is obvious that the invention may be adapted to any desired form of centrifugal casting ma--.

forms the other electrode and which may be brought into proximity to the metallic button, and the means for controlling the amount of current passing through the circuit. These three elements may be used in. a large variety of forms and. with av large variety of apparatus, and the forms which I have shown are merely illustrative of two applications of my invention.

It will of course be understood that the investment with its sprue opening constitutes a casting flask as used in conjunction with my improved means for melting the metal to be cast within the flask.

The apparatus previously described is particularly useful as a substitute in dental oflices for the gasolene blow pipe and the acetylene and oxyhydrogen blow pipes. The objections to the gasolene blow pipe are many. It is relatively too slow in its from five to thirty minutes to complete the operation of casting by a gasolene blow pipe. It will not heat gold sufiiciently to cast into cold investment and do accurate work. Casting in a cold investment is advocated by the dental profession today as thus the minimum amount of contraction or expansion is caused in the investment. Furthermore, the gasolene blow pipe cannot fuse or refine platinum or iridium. There is, of course, constant danger of fire from leakage of the gasolene. In use, a gasolene blow pipe is very dirty to handle and there is considerable odor.

While the acetylene and oxyhydrogen blow pipes give sufficient heat to fuse gold and do good casting, they are much slower than electricity in doing the work. Furthermo're, theyexpense of installation and operation is very large, and they create a disagreeable odor and this is particularly true of the acetylene blow pipe. Furthermore, there is constant danger of explosion and they requir'e considerable space to install and operate. Neither the acetylene or the oxyhydrogen blow pipe will fuse platinum or iridium to a degree suiiicient for the casting operation. By using the electric arc for fusing metals the casting of metal is very much facilitated, and in actual operation it only takes from two to five seconds to complete the casting, thus saving from live to thirty minutes at each casting operation. The gold or other precious metals are heated almost instantly to a degree almost sufficient that they may be cast in a cold investment. Platinum or iridium may be refined or cast in the same manner as gold.

The device is cheap to install and operate; the cost of op'eration is very slight; and it takes up very little space and it is particularly clean. It is advisable to use the rheostat in my apparatus because by its means various degrees of heat may be attained, which is requisite because of the different amounts and fusing points of the metals that may be used. 'VVhere only a small quantity of metal is to be fused, less current is necessary than with larger amounts.

All of the investment compounds used in dental casting contain a little iron. Hence when molten metal is cast, it is slightly contaminated by the iron, and about three casts with one piece of gold is all that should be made until the gold is refined. This takes from five to thirty minutes of hard Work and some expense. With my electrical cast-- ing apparatus the heat is sufiicient to burn out this iron at each casting operation which eliminates these periods of refining. While the fusing point of iron is higher than that of gold, yet the specific gravity ofgold is approximately 19?; and that of iron 7% and hence the lighter metal will rise to the surface of the molten mass and consequently burn out first. It will be noted that the heat is communicated to theinvestment material by reason of the intimate contact between the investment material and the carbon block or electrode and between said carbon block or electrode and investment ring, thus heating the investment and at the same time providing means for melting the precious metal.

Having thus described-my invention, what I claim is:

1.. The combination with an investment ring comprising a cylindrical metallic body having an approximately uniform diameter and open at its opposite ends and investment material disposed in the ring, of a carbon block having removable sliding engagement with one end of the ring and fitting in close contact with the investment material, the investment material and. the carbon block having a sprue passage and the carbon block being hollowed out on one face to provide a depression for the reception of metal to be fused, a relatively movable electrode of high resistance material and having a non-conductive handle, and electrical connections between the carbon block of high resistance materiai and a source of current and between the movable electrode and said source.

2. In a dental casting apparatus the com.- bination with a rotatably mounted bar, means for rotating the bar, a latch detachabiy holding the bar from rotation, and a metallic sleeve mounted upon the bar and cut away upon its upper face, of an investment ring insertible into said sleeve, investment material disposed within the ring and constituting a flask having a sprue opening, a body of high resistance material constituting an electrode and removably supported in said sleeve in contact with the invest-v Iment material and the ring, said body having a longitudinally extending recess in its of the investment, a rod of high resistance material constituting a movable electrode and adapted'to be brought into contiguity with the material in said recess of the block, and electrical connections between the rod and the source of current and between said block and the source of current.

signature in the presence of two witnesses.

LENVIS H. LANIER. Witnesses W. M. COPELAND,

H. E. STEELE.

In testimony whereof I hereunto ailix my 

